TSP Allocation by Age: L Fund vs Custom Portfolio Strategies (2026)
Bottom Line Up Front: Under 40, weight heavily toward equities — 60/20/20 (C/S/I) is a widely-used custom split, 100% C Fund is a simpler alternative, and an age-appropriate Lifecycle Fund (L 2065 to L 2075) handles the glide path automatically. Between 40 and 50, an L Fund matched to your retirement year is usually appropriate. Within 10 years of retirement, L 2035 or L Income. The 2026 elective deferral limit is $24,500; catch-up at 50+ is $8,000. (IRS Notice 2025-67)
Sources: TSP.gov, TSP Fund Performance, BRS Calculator
What Allocation by Age Actually Means
Your TSP allocation should change as your time horizon shrinks. In your 20s and 30s, a 30%+ drawdown does not threaten retirement — it threatens a few years of paper losses you can ride out. At 60, the same drawdown can force you to sell into the loss to fund withdrawals.
Two valid approaches:
- Lifecycle (L) Funds — pre-mixed, automatically glide more conservative each quarter as the target date approaches. Set once, ignore.
- Custom portfolio — pick your own mix of C, S, I, F, and G Funds. More control, requires an annual rebalance.
Either approach beats the most common mistake: leaving the balance entirely in G Fund for decades.
The Five Core Funds
G Fund (Government Securities)
- What it holds: Specially-issued, non-marketable U.S. Treasury notes and bonds.
- Risk: No nominal loss possible.
- 2025 return: 4.44%. (TSP Rates of Return)
- Use case: Capital preservation; not long-term growth.
F Fund (Fixed Income / U.S. Bond Index)
- What it holds: Bloomberg U.S. Aggregate Bond Index.
- Risk: Low to moderate. Lost 12.8% in 2022 when rates rose sharply.
- 2025 return: 7.21%.
- Use case: Stability slice in a balanced portfolio near retirement.
C Fund (Common Stock — S&P 500)
- What it holds: The S&P 500.
- Risk: Moderate to high. Periodic 30%+ drawdowns; full recovery typically within 2–3 years.
- 2025 return: 17.85%.
- Use case: Core long-horizon growth holding.
S Fund (Small/Mid-Cap U.S. Stock)
- What it holds: Dow Jones U.S. Completion TSM Index — every U.S. listed stock outside the S&P 500.
- Risk: Higher than C Fund.
- 2025 return: 11.38%.
- Use case: A 10–20% slice for additional small-cap exposure.
I Fund (International Stock)
- What it holds: As of 2024, an MSCI ACWI IMI ex-U.S. ex-China ex-Hong Kong index. The benchmark broadened in 2024 from the prior EAFE-only index.
- Risk: Moderate.
- 2025 return: 32.45% — the strongest single-year return for the I Fund since the fund's inception, driven by the broader benchmark, a weaker dollar, and strong non-U.S. markets.
- Use case: A 10–20% slice for non-U.S. diversification.
Lifecycle Funds in 2026
L Funds rebalance daily to a target allocation that becomes more conservative each quarter as the retirement date approaches.
The far-dated funds (L 2055, L 2060, L 2065, L 2070, L 2075) hold less than 1% combined in G + F bonds; the rest is split across C, S, and I. As the target date moves closer, the glide path adds bonds and G Fund. (TSP Lifecycle Funds fact sheet)
| Fund | Withdrawal window | Default for birth year |
|---|---|---|
| L 2075 | 2073+ | 2009 or later |
| L 2070 | 2068–2072 | 2005–2009 |
| L 2065 | 2063–2067 | 2000–2004 |
| L 2060 | 2058–2062 | 1995–1999 |
| L 2055 | 2053–2057 | 1990–1994 |
| L 2050 | 2048–2052 | 1985–1989 |
| L 2045 | 2043–2047 | 1980–1984 |
| L 2040 | 2038–2042 | 1975–1979 |
| L 2035 | 2033–2037 | 1970–1974 |
| L 2030 | 2028–2032 | 1965–1969 |
| L Income | retired or near retirement | 1959 or earlier |
Tradeoff vs. a custom portfolio. An L Fund matched to your age is more conservative than a 100% C Fund position. Over 30+ years that costs some growth; the trade is less volatility and no need to rebalance manually. Past Mind the Gap-style research from Morningstar suggests target-date investors typically capture more of their fund's stated return than do-it-yourself investors, because they don't react to short-term news.
Allocation by Age and Career Stage
These are starting points. Risk tolerance, planned retirement date, deployment status, and other household assets all matter.
Ages 18–30 — Heavy Equities (90–100%)
Custom: 60% C / 20% S / 20% I. Simpler alternatives: 100% C Fund, or L 2065 to L 2075.
You have 30+ years until retirement. Short-term volatility does not threaten the outcome; sitting in G Fund for that horizon does.
A real-money illustration: an E-3 contributing 5% of base pay (roughly $175/month at current rates) for 40 years reaches roughly $1.0 million at a 10% nominal return, versus roughly $200,000 at 3%. Same contributions, very different real-life outcome — driven entirely by allocation, not by saving more.
Ages 30–40 — Still Heavy Equities (80–90%)
Custom: 50% C / 20% S / 20% I / 10% F. Simpler alternative: L 2055 or L 2060.
20–30 years to retirement. Add a small F slice to dampen volatility, but stay equity-dominant.
If you are within 6 months of a deployment and prefer not to manage TSP from theater, holding allocation steady through the deployment is fine — you do not need to shift to G Fund pre-deployment unless your specific risk tolerance demands it.
Ages 40–50 — Gradual Shift (70–80%)
Custom: 45% C / 15% S / 15% I / 15% F / 10% G. Simpler alternative: L 2045 or L 2050.
10–20 years to retirement. Begin adding stability. Each year after 45, shift roughly 2–3% from stocks to bonds.
Ages 50–60 — Conservative Growth (50–65%)
Age 50–55 custom: 35% C / 10% S / 10% I / 25% F / 20% G. Age 56–60 custom: 30% C / 5% S / 10% I / 30% F / 25% G. Simpler alternative: L 2035 or L 2040.
Approaching retirement. Balance growth with preservation. Sequence-of-returns risk — a market drop in the first few years of withdrawals — becomes the dominant concern.
Ages 60+ — Preservation and Income (30–40%)
Custom: 20% C / 10% I / 40% F / 30% G. Simpler alternative: L Income.
Withdrawing or about to. A 4% initial withdrawal rate is the conventional starting point (Trinity Study), and keeping 1–2 years of withdrawals in G Fund as a buffer reduces the need to sell stocks during a down year.
Lifecycle Fund vs. Custom Portfolio — A Comparison
Imagine a 25-year-old E-4 who contributes $200/month for 35 years, with no contribution increase.
Option A: L 2060 (Lifecycle) Starts ~99% stocks, glides toward conservative by age 60. Expected blended return ≈ 7.5%/year. Projected balance: roughly $450,000.
Option B: Custom portfolio with no glide path 60% C / 20% S / 20% I held for the full 35 years. Expected blended return ≈ 9%/year (assuming long-run averages). Projected balance: roughly $650,000.
Option C: Custom portfolio with a glide path 60/20/20 until 40, transitions to age-appropriate L Fund afterward. Expected blended return ≈ 8.5%. Projected balance: roughly $580,000.
These projections assume long-run averages hold. They will not — actual market sequences will do something else. The point is that a long horizon is the largest determinant of outcome, and that L Funds give up some upside in exchange for a smoother glide path. Either choice is reasonable; sitting in G Fund for 35 years is not.
Special Situations
Deploying soon
You can manage TSP from anywhere with internet access. There is no operational reason to shift to G Fund pre-deployment. If your personal risk tolerance is low and you want a buffer against being unable to react to a 2008-style crash mid-deployment, a 10–20% G Fund tilt is a reasonable hedge — but understand the tradeoff in expected return.
Separating or retiring within 2 years
Shift toward 40–50% G + F over the final two years to reduce sequence-of-returns risk. The goal is not maximum return; it is making sure a market drop right before withdrawals begin doesn't permanently impair the balance.
Market crash in progress
The instinct to sell to G Fund after a 20% drop is the most expensive instinct in personal finance. Long-horizon historical data shows post-drawdown buyers materially outperformed sellers in 1987, 2000, 2008, and 2020.
A defensible response during a crash:
- Confirm your allocation still matches your time horizon.
- If it does, leave it alone.
- If you have new money to contribute, contribute.
- Re-check in 6 months.
BRS vs. Legacy: How It Affects Allocation Strategy
Blended Retirement System (BRS)
Service members who joined on or after January 1, 2018 are under BRS. The DoD matches up to 5% of base pay into TSP. Service members are auto-enrolled at 5% into an age-appropriate Lifecycle Fund — not the G Fund. (TSP Bulletin 20-U-1)
The match is the highest-priority TSP behavior. Contributing less than 5% leaves the match on the table.
Legacy / High-3 (joined before 2018)
No TSP match. Pension eligibility at 20 years of service is the dominant retirement asset. TSP still matters — pension cost-of-living adjustments lag inflation, and TSP grows tax-advantaged. Aim for 10–15% of base pay if cash flow allows.
Common Mistakes That Cost Money
Leaving the default unchanged after years of service
Long-tenured participants may still be 100% G Fund from earlier defaults. The fix takes ten minutes — sign in, rebalance account, change contribution allocation.
Chasing last year's winner
Picking the highest-returning fund of the prior year is a known recipe for under-performance. The I Fund returned 32.45% in 2025; that does not mean putting 100% in I in 2026 is the right move. Diversification across C/S/I works in part because no one knows which slice will lead next.
Panic-selling during crashes
Locking in losses by moving to G Fund mid-drawdown is the single most damaging behavior an investor can adopt. Stocks have always recovered eventually. Selling during the drop guarantees you participate in the loss but not the recovery.
Ignoring TSP because of an expected pension
Pension cost-of-living adjustments lag real inflation. TSP fills the gap. Both retirement systems benefit from a well-allocated TSP balance.
Not contributing enough for the BRS match
Under BRS, contributing less than 5% of base pay forfeits part of the DoD match. The match is part of compensation; declining it has the same economic effect as taking a pay cut.
How to Rebalance Your TSP
1. Sign in at tsp.gov
Account login on the homepage.
2. Check current allocation
Account Activity → Account Balance shows current fund breakdown.
3. Rebalance current balance
Account Activity → Rebalance Account. Enter target percentages summing to 100%. This moves existing balance.
4. Update contribution allocation
Account Activity → Contribution Allocation. This applies to future contributions only. Both steps are required if you want existing and new money in the same allocation.
5. Set an annual reminder
Once a year is sufficient. Calendar reminder, January, ten minutes.
Real-World Examples
Example 1: E-4, age 22, just started TSP
- Base pay roughly $2,800/month
- Current TSP balance: $3,000
- BRS, contributing 5% (matched)
Suggested: 65% C / 20% S / 15% I, or L 2065/L 2070. Strategy: raise contribution by 1% at each promotion. By E-6 a 10–15% rate is realistic.
Example 2: O-3, age 35, moderate TSP balance
- Base pay roughly $7,500/month
- Current TSP balance: $120,000
- Legacy / High-3 (no match)
- Currently 100% L 2050
Suggested: 55% C / 20% S / 15% I / 10% F. Or stay in L 2050 and contribute more aggressively. Both are defensible.
Example 3: E-7, age 48, close to retirement
- Base pay roughly $5,200/month
- Current TSP balance: $450,000
- Retiring at 55 (33 years of service)
- Currently 70% C/S/I, 30% G/F
Suggested: 40% C / 10% I / 30% F / 20% G, with another 5% shift toward bonds annually until separation. By age 55, target a 30% stock / 70% bonds-and-G allocation in preparation for the early-retirement years.
A Note on 2026 Changes
- 2026 elective deferral limit: $24,500. Catch-up at age 50+: $8,000 (combined limit $32,500). Higher catch-up of $11,250 for ages 60–63. Source: IRS Notice 2025-67.
- Mandatory Roth catch-up for high earners. Starting January 1, 2026, participants whose 2025 FICA wages exceeded $150,000 must designate any catch-up contributions as Roth (after-tax). Source: Treasury final regulations on SECURE 2.0 Roth catch-up rule.
If you turn 50 in 2026 and earned over $150,000 in 2025, your catch-up portion needs to be Roth.
Action Steps
- Check current allocation at tsp.gov.
- Pick a target allocation from the by-age section above.
- Rebalance current balance and update contribution allocation — both are required to keep existing and future contributions aligned.
- Confirm BRS match if you joined on or after January 1, 2018. Anything below 5% leaves part of the match unclaimed.
- Set a yearly reminder to review.
Verification & Sources
- TSP fund composition and performance: tsp.gov/fund-performance, tsp.gov/funds-lifecycle
- 2026 contribution limits: IRS Notice 2025-67, November 13, 2025
- BRS auto-enrollment defaults: TSP Bulletin 20-U-1
- SECURE 2.0 Roth catch-up rules: Treasury final regulations, October 2025
- Mind the Gap investor return study: Morningstar (annual)
Last verified: May 4, 2026 Date modified: May 4, 2026
Allocation matters less than two other behaviors: contributing enough to capture the full BRS match, and leaving the allocation alone for decades. The best portfolio is one you will actually stick with through the next bear market.